Additive manufacturing, also referred to herein as three dimensional (3D) printing, is a process that creates or augments a three dimensional object by laying down successive layers of material, often on a print bed, to form an object with a desired design. Although a wide variety of additive manufacturing techniques have been developed, in recent years systems that employ fused filament fabrication (FFF) (also known as FUSED DEPOSITION MODELING® or FDM®) have grown increasingly popular. In general, FFF systems form three dimensional objects from one or more raw filamentary part materials using a computer controlled print head that includes an extrusion nozzle. More specifically, based on digital design of a desired 3D object, a computer causes a print head to move in the x, y, and z dimensions, e.g., over a print bed. At the same time, raw part material (e.g., in the form of a spooled filament) is fed into the print head. The raw part material is softened (e.g., by heating above its glass transition temperature), extruded through an extrusion nozzle, and deposited as a “layer” or “path” e.g., on the print bed or a previously deposited layer. Following its deposition, the deposited material solidifies as its temperature drops, and may also fuse to adjacent surfaces, e.g., of a previously deposited layer, the print bed, etc. After a layer of the object is formed, the position of the print head may then be incremented along the z-axis (e.g., perpendicular an x-y plane), and the process may then be repeated iteratively until the object is completely built up.
With the foregoing in mind, parts formed by many additive manufacturing techniques and in particular fused filament fabrication tend to have physical property limitations, particularly in the direction transverse to the material deposition direction (also referred to herein as the “machine direction). For example parts manufactured via fused filament fabrication may exhibit directionally dependent (i.e., anisotropic) tensile strength and/or shear flow properties, with such properties being relatively weak in the direction transverse to the machine direction. As a result, the physical properties of parts formed by additive manufacturing processes may be weaker than similar parts manufactured by injection molding or casting, wherein the full volume of a part may be formed simultaneously and homogenously. Parts formed by additive manufacturing processes such as fused filament fabrication may therefore be unsuitable and/or undesirable for certain applications.
Although the following detailed description will proceed with reference being made to illustrative embodiments, many alternatives, modifications, and variations thereof will be apparent to those skilled in the art.